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An experimental study of drag and heat transfer reductions in turbulent pipe flows for polymer and surfactant solutions.

机译：用于聚合物和表面活性剂溶液的湍流管道中阻力和热传递减少的实验研究。

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摘要

A new, simpler, and more accurate scaling correlation is proposed. This correlation is applicable to most dilute polymer solutions, and to some surfactant solutions as well. The existence of two clearly different groups of fluids that scale according to different correlations is established, and it does not necessarily correspond to the distinction between polymers and surfactants. Also, the diameter effect on heat transfer is eliminated as a separate problem for both groups of fluids. The diameter effect for the Type B drag reduction behavior is also revised. In this case, the diameter effect disappears at high Reynolds numbers far from the retro-onset, suggesting that the diameter effect exists only when the fluid properties responsible for the DR phenomenon vary with increasing velocity.; A relationship between the DR and HTR for polymer and surfactant solutions is established under asymptotic and intermediate conditions, showing that, as suspected, the Reynolds analogy for drag-reducing fluids is not likely to hold, though a straightforward relationship may exist (i.e., that the turbulent Prandtl number is different than 1, but constant). The possibility of a decoupling between the two transfer processes was also investigated. Experiments around the onset region and the region close to asymptotic conditions showed that a decoupling between DR and HTR is not likely to occur. Additionally, an improved drag-reducing asymptote and a new heat transfer asymptote are proposed.; The temperature profiles are used to estimate the value of the turbulent Prandtl number (Prt) for polymers and surfactants. The Pr t is constant throughout the pipe cross-section and has a value between 5 and 8 for asymptotic conditions. Also, the increase in the drag-reducing ability of drag-reducing fluids is clearly distinguished in two patterns. The first, the classical Virk's 3-layer profile model; the second, a “fan type” pattern, which exhibits an increasing slope of the buffer layer with increasing DR (and HTR). Finally, it is seen that, the effect of Pr is stronger for the Type B than for Type A drag-reducing behaviors, what causes a large sublayer thickening, and, thus, a reduction in the eddy diffusivities of heat and momentum in the outer region.
机译：提出了一种新的，更简单，更准确的缩放相关性。这种相关性适用于大多数稀聚合物溶液，也适用于某些表面活性剂溶液。确定存在两种明显不同的流体，它们根据不同的相互关系成比例地存在，并且不一定对应于聚合物和表面活性剂之间的区别。同样，消除了直径对热传递的影响，作为两组流体的单独问题。还修改了 B型减阻行为的直径效果。在这种情况下，直径效应在远离雷诺数的高雷诺数处消失，这表明直径效应仅在负责DR现象的流体性质随速度增加而变化时存在。在渐近和中间条件下，建立了聚合物和表面活性剂溶液的DR和HTR之间的关系，这表明，尽管可能存在直接的关系，但据怀疑，减阻流体的雷诺兹类比不太可能成立（<斜体>即。，湍流的Prandtl数不同于1，但恒定）。还研究了两个转移过程之间去耦的可能性。围绕起病区域和接近渐近条件的区域进行的实验表明，DR和HTR之间不太可能发生解耦。另外，提出了一种改进的减阻渐近线和一种新的传热渐近线。温度曲线用于估计聚合物和表面活性剂的湍流普朗特数（Pr t ）的值。 Pr t 在整个管道横截面上都是恒定的，对于渐近条件，其值在5到8之间。同样，减阻流体的减阻能力的增加清楚地以两种方式区分。首先，经典的维克三层轮廓模型；第二种是“扇型”图案，随着DR（和HTR）的增加，缓冲层的斜率也增加。最后，可以看出，对 B型而言，Pr的作用要比对 A型的减阻行为更强，导致较大的亚层增厚，因此，减少了外部区域热量和动量的涡流扩散。

著录项

  • 作者

    Aguilar-Mendoza, Guillermo.;

  • 作者单位

    University of California, Santa Barbara.;

  • 授予单位 University of California, Santa Barbara.;
  • 学科 Engineering Mechanical.
  • 学位 Ph.D.
  • 年度 1999
  • 页码 363 p.
  • 总页数 363
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 机械、仪表工业;
  • 关键词

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